/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jms.config;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.lang.Nullable;
import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
import org.springframework.messaging.handler.annotation.support.MessageHandlerMethodFactory;
import org.springframework.util.Assert;

/**
 * Helper bean for registering {@link JmsListenerEndpoint} with a {@link JmsListenerEndpointRegistry}.
 *
 * @author Stephane Nicoll
 * @author Juergen Hoeller
 * @see org.springframework.jms.annotation.JmsListenerConfigurer
 * @since 4.1
 */
public class JmsListenerEndpointRegistrar implements BeanFactoryAware, InitializingBean {

    @Nullable
    private JmsListenerEndpointRegistry endpointRegistry;

    @Nullable
    private MessageHandlerMethodFactory messageHandlerMethodFactory;

    @Nullable
    private JmsListenerContainerFactory<?> containerFactory;

    @Nullable
    private String containerFactoryBeanName;

    @Nullable
    private BeanFactory beanFactory;

    private final List<JmsListenerEndpointDescriptor> endpointDescriptors = new ArrayList<>();

    private boolean startImmediately;

    private Object mutex = endpointDescriptors;


    /**
     * Set the {@link JmsListenerEndpointRegistry} instance to use.
     */
    public void setEndpointRegistry(@Nullable JmsListenerEndpointRegistry endpointRegistry) {
        this.endpointRegistry = endpointRegistry;
    }

    /**
     * Return the {@link JmsListenerEndpointRegistry} instance for this
     * registrar, may be {@code null}.
     */
    @Nullable
    public JmsListenerEndpointRegistry getEndpointRegistry() {
        return this.endpointRegistry;
    }

    /**
     * Set the {@link MessageHandlerMethodFactory} to use to configure the message
     * listener responsible to serve an endpoint detected by this processor.
     * <p>By default, {@link DefaultMessageHandlerMethodFactory} is used and it
     * can be configured further to support additional method arguments
     * or to customize conversion and validation support. See
     * {@link DefaultMessageHandlerMethodFactory} javadoc for more details.
     */
    public void setMessageHandlerMethodFactory(@Nullable MessageHandlerMethodFactory messageHandlerMethodFactory) {
        this.messageHandlerMethodFactory = messageHandlerMethodFactory;
    }

    /**
     * Return the custom {@link MessageHandlerMethodFactory} to use, if any.
     */
    @Nullable
    public MessageHandlerMethodFactory getMessageHandlerMethodFactory() {
        return this.messageHandlerMethodFactory;
    }

    /**
     * Set the {@link JmsListenerContainerFactory} to use in case a {@link JmsListenerEndpoint}
     * is registered with a {@code null} container factory.
     * <p>Alternatively, the bean name of the {@link JmsListenerContainerFactory} to use
     * can be specified for a lazy lookup, see {@link #setContainerFactoryBeanName}.
     */
    public void setContainerFactory(JmsListenerContainerFactory<?> containerFactory) {
        this.containerFactory = containerFactory;
    }

    /**
     * Set the bean name of the {@link JmsListenerContainerFactory} to use in case
     * a {@link JmsListenerEndpoint} is registered with a {@code null} container factory.
     * Alternatively, the container factory instance can be registered directly:
     * see {@link #setContainerFactory(JmsListenerContainerFactory)}.
     *
     * @see #setBeanFactory
     */
    public void setContainerFactoryBeanName(String containerFactoryBeanName) {
        this.containerFactoryBeanName = containerFactoryBeanName;
    }

    /**
     * A {@link BeanFactory} only needs to be available in conjunction with
     * {@link #setContainerFactoryBeanName}.
     */
    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        this.beanFactory = beanFactory;
        if (beanFactory instanceof ConfigurableBeanFactory) {
            this.mutex = ((ConfigurableBeanFactory) beanFactory).getSingletonMutex();
        }
    }


    @Override
    public void afterPropertiesSet() {
        registerAllEndpoints();
    }

    protected void registerAllEndpoints() {
        Assert.state(this.endpointRegistry != null, "No JmsListenerEndpointRegistry set");
        synchronized (this.mutex) {
            for (JmsListenerEndpointDescriptor descriptor : this.endpointDescriptors) {
                this.endpointRegistry.registerListenerContainer(
                        descriptor.endpoint, resolveContainerFactory(descriptor));
            }
            this.startImmediately = true;  // trigger immediate startup
        }
    }

    private JmsListenerContainerFactory<?> resolveContainerFactory(JmsListenerEndpointDescriptor descriptor) {
        if (descriptor.containerFactory != null) {
            return descriptor.containerFactory;
        } else if (this.containerFactory != null) {
            return this.containerFactory;
        } else if (this.containerFactoryBeanName != null) {
            Assert.state(this.beanFactory != null, "BeanFactory must be set to obtain container factory by bean name");
            // Consider changing this if live change of the factory is required...
            this.containerFactory = this.beanFactory.getBean(
                    this.containerFactoryBeanName, JmsListenerContainerFactory.class);
            return this.containerFactory;
        } else {
            throw new IllegalStateException("Could not resolve the " +
                    JmsListenerContainerFactory.class.getSimpleName() + " to use for [" +
                    descriptor.endpoint + "] no factory was given and no default is set.");
        }
    }

    /**
     * Register a new {@link JmsListenerEndpoint} alongside the
     * {@link JmsListenerContainerFactory} to use to create the underlying container.
     * <p>The {@code factory} may be {@code null} if the default factory has to be
     * used for that endpoint.
     */
    public void registerEndpoint(JmsListenerEndpoint endpoint, @Nullable JmsListenerContainerFactory<?> factory) {
        Assert.notNull(endpoint, "Endpoint must not be null");
        Assert.hasText(endpoint.getId(), "Endpoint id must be set");

        // Factory may be null, we defer the resolution right before actually creating the container
        JmsListenerEndpointDescriptor descriptor = new JmsListenerEndpointDescriptor(endpoint, factory);

        synchronized (this.mutex) {
            if (this.startImmediately) {  // register and start immediately
                Assert.state(this.endpointRegistry != null, "No JmsListenerEndpointRegistry set");
                this.endpointRegistry.registerListenerContainer(descriptor.endpoint,
                        resolveContainerFactory(descriptor), true);
            } else {
                this.endpointDescriptors.add(descriptor);
            }
        }
    }

    /**
     * Register a new {@link JmsListenerEndpoint} using the default
     * {@link JmsListenerContainerFactory} to create the underlying container.
     *
     * @see #setContainerFactory(JmsListenerContainerFactory)
     * @see #registerEndpoint(JmsListenerEndpoint, JmsListenerContainerFactory)
     */
    public void registerEndpoint(JmsListenerEndpoint endpoint) {
        registerEndpoint(endpoint, null);
    }


    private static class JmsListenerEndpointDescriptor {

        public final JmsListenerEndpoint endpoint;

        @Nullable
        public final JmsListenerContainerFactory<?> containerFactory;

        public JmsListenerEndpointDescriptor(JmsListenerEndpoint endpoint,
                                             @Nullable JmsListenerContainerFactory<?> containerFactory) {

            this.endpoint = endpoint;
            this.containerFactory = containerFactory;
        }
    }

}
